AVS 53rd International Symposium
    Advanced Surface Engineering Thursday Sessions
       Session SE2-ThM

Paper SE2-ThM8
Cr-B-N Coatings Deposited by Cathodic Arc Evaporation

Thursday, November 16, 2006, 10:20 am, Room 2007a

Session: Hard and Nanocomposite Coatings: Synthesis, Structure, and Properties
Presenter: K. Polychronopoulou, Christian Doppler Laboratory for Advanced Hard Coatings
Authors: K. Polychronopoulou, Christian Doppler Laboratory for Advanced Hard Coatings
J. Neidhardt, Christian Doppler Laboratory for Advanced Hard Coatings
B. Sartory, Christian Doppler Laboratory for Advanced Hard Coatings
R. Kaindl, Christian Doppler Laboratory for Advanced Hard Coatings
R. Tessardi, Christian Doppler Laboratory for Advanced Hard Coatings
C. Rebholz, University of Cyprus
M. O Sullivan, Plansee SE
A.E. Reiter, Balzers AG
C. Mitterer, Christian Doppler Laboratory for Advanced Hard Coatings
Correspondent: Click to Email
Transition metal boron nitride (Me-B-N) coatings receive increasing attention for their excellent combination of mechanical, chemical and tribological properties. Thus, this study presents nanocomposite Cr-B-N coatings deposited onto various substrates by high-rate reactive cathodic arc evaporation from Cr/B (80/20 at%) targets at 500°C using a commercial Balzers RCS system. The total pressure (Ar+N@sub 2@) was kept constant at 2 Pa, while the N@sub 2@ fraction was varied between 0 and 1. The coating composition and microstructure and mechanical as well as tribological properties were determined. X-ray diffraction studies revealed that Cr-B-N coatings deposited in a range of N@sub 2@ fractions from 1/8 - 1 contain randomly orientated CrN crystallites. No crystalline BN or Cr@sub 2@N phases were identified, whereas after vacuum annealing at 700°C during stress-temperature measurements peaks attributable to the Cr@sub 2@N phase emerged. The as-deposited coatings are with 2-3 GPa in a compressive stress state for higher N@sub 2@ fractions, while the hardness and elastic modulus values range from 18 to 23 GPa and 210 to 240 GPa, respectively. During ball-on-disc tests, these coatings revealed a coefficient of friction decreasing from 0.8 to 0.4; values between 0.5-0.6 were observed at an elevated testing temperature of 500°C. Raman investigations after tribological experiments revealed mainly chromium oxide suggesting a predominantly oxidative wear mechanism.